The skeleton forms the supporting framework of the body and consists of separate bones joined together by means of cartilage, Ligaments and muscles.

The parts of the skeleton are:

• Skull
• Backbone or spine
• The ribs and breast bone
• The upper limbs
• The pelvis
• The lower limbs bones

THE SKULL:

The skull is the skeleton of the head and is made up of the following bones:

• One on the top called the dome
• One in the front corresponding to the face called the frontal
• Two - One on either side called arietals
• Two - One on either side below the parietals - called the temporals
• One behind corresponding to the back of the head called the occipital
• Two forming the roof of the mouth or the upper jaw

All these bones are joined together and form the skull. The skull contains the brain and has a bony provision for formation of eyes, ears and nose. It is rounded in shape and has an opening at the bottomthrough which the spinal cord enters the vertebral column. ts lower portion also forms the upper jaw. The lower jaw is a separate single bone which is attached to the skull and consist of one horizontal portion in the centre and two vertical portions at the sides. The junction of the vertical and the horizontal portions is commonly referred to as the angle of the jaw.

One has to be familiar with the position of the angle of the jaw because this has to be pressed forward in case of an unconscious victim to prevent the fall back of the tongue which impedes the airway.

When a blow on the head causes bleeding from torn vessels inside the closed box of brain, the blood is unable to escape and gets collected and presses the brain tissue. This leads to headache , irritability, unconsciousness and may cause death.

THE BACKBONE OR SPINE

It consists of 33 small rounded pieces of bones each called a vertebra, placed one above the other

• 7 in the back region ( Cervical)
• 12 in the neck region (Thoracic or Dorsal)
• 5 in the waist region (Lumbar)
• 5 in the hip region (Sacral)
• 4 in the tail region ( Coccygial)

In between each pair of vertebrae there is a thick piece of cartilage called DISC which allows movement as well as acts as a shock absorber. There is a central canal through which the spinal cord passes and carries nerve impulses to and fro form the brain.

If there is any injury, one vertebra may be displaced over another, thus the spinal cord is pressed or cut causing paralysis, due to interruption in the pathway of nerves.

THE RIBS AND BREAST BONE

There are 12 pairs of ribs which are attached to the corresponding vertebrae at the back. The first seven pairs of these ribs are attached to the breast bone in front, 8th , 9th and 10th ribs are attached to the rib above and the last 2 ribs dat is 11th and 12th have no attachment in front and are known as floating ribs.

THE UPPER LIMBS AND SHOULDER

The bones are:

• The collar bone (Clavicle) one on each side between upper part of the breast bone on the front and shoulder blade.
• The shoulder blade (scapula)

The clavicle is a very brittle bone and is the common site of fracture. ts function is to keep away the upper limb from the chest.

SHOULDER BLADE (SCAPULA)

One on either side on the upper and outer part on the back of  the chest.

The bones of the upper limbs are:

• Upper arm bone (humerus)
• Forearm bones. There are two bones:

i) Radius (Outer side of forearm)
ii) Ulna (Inner side of forearm)

• The joint between upper arm and forearm is called elbow joint.
• There are 8 carpal bones at the wrist and five metacarpal bones in the palm of the hand.
• There are 3 small bones in each finger called phalange and 2 bones for each thumb.

THE PELVIS AND LOWER LIMB

• The two hip bones one on either side joined together form the pelvis.The pelvis forms the basin shaped cavity which contains intestines, urinary bladder and reproductive organs. there are two sockets one of either side of the pelvis , where the thigh bones join forming the hip joint.
• Femur or the thigh bone is the longest and strongest bone in the body. Its upper end forms a part of the hip joint while its lower end forms a part of the knee joint. The upper end of the femur is easily liable to fracture in old age due to even minor falls.
• Knee cap (Patella) is a small bone over the front of the knee joint lying loosely in the muscles, ligaments and under the skin.

The Bones of the leg are :

• The Shin bone (Tibia)).:The Tibia extends from the knee joint to the ankle point, in both of which joints it plays an important part. Its sharp edge can be felt immediately beneath the skin of the front of the leg.
• The Brooch bone (Fibula) :The fibula lies on the outer side of the tibia. It doesn not enter into the formation the the knee joint but its lower end forms   forms the outer part of the ankle joint.

The Bones of the foot are:

• These comprise 7 irregular bones:
• Tarsals at the 'instep.
• The largest,  the heel bone and the uppermost forms the lower part of the ankle joint.
• Five long bones (metatarsus) infront o the instep support the toes
• The toe bones (phalanges) are 14 in number - two in the big toe and three in each of the other four toes.

JOINTS

Joints are at the junction of two or more bones. There may be no movements as in skull or there may be free movements as in knee , elbow, shoulder and hip joints. n movable joints, the ends of the bones are covered by cartilage and is overall again encased in capsule with some lubricant material inside the joint.

MUSCLES

Muscles to the layman mean flesh and are primarily meant to produce movement of the limbs and organs. There are broadly two types of muscles:

Voluntary muscles which can cause movement under the dictates of will
nvoluntary muscles like those found in the heart which continue to work even without the dictates of will

NERVES AND STIMULI

The muscles go into action called contraction by stimuli of nerves arising from brain and spinal cord carrying motor impulses. Damage to nerves results in paralysis of the muscles just as cutting the wire between a battery and the bulb impedes the flow of electricity.

LIGAMENTS

Thickened portions of the joint capsule are called ligaments. They check movements beyond normal permissible limits.f there is simple injury to the ligaments of the joints , it is called sprain.

CONNECTIVE TISSUE

Connective tissue consists of yellow elastic and white fibrous tissue intermixed in varying proportions. It is present in many parts of the body and forms a layer between the skin and underlying flesh all over the body, Fat being contained between its meshes, often in large quantities. The chief use of connective tissue is to blind parts together.

The skin covers the whole of the body and protects the underlying structures. It consists of two layers , the outer or hard layer (cuticle) and the inner layer ( true skin or dermis). n the latter are numerous glands which secrete sweat the evaporation of which from the surface of the skin cools it and helps to regulate the temperature of the body.

EYE

The eyes are situated in sockets in the front of the skull and covered with folds of skin (the eyelids) from which the eyelashes project. The inside of the eyelids and front of the eye are covered by a smooth membrane (conjuctiva) and are washed and are kept moist by tear fluid. through the transparent part of the eye( cornea) can be seen a colored circular diagphragm (the iris) with a round hole (the pupil). The latter varies in size with the amount of light passing through it. Behind the pupil is the lens of the eye which focuses rays of the light on to the light sensitive part of the eye (retina).

EAR

The ear consists of three parts:

• The outer ear is that part which can be seen projecting form the side of the skull, together with the canal which leads to the eardrum.
• The middle ear situated inside the skull, receives and transmits to the inner ear sound waves concerned in hearing. It also communicates with the back of the nose and throat by the ustachian tube, which opens in swallowing.
• The inner ear is embedded inside the skull and is concerned with the sense of balance in addition to the sense of hearing.

The outer ear is separated from the middle ear by the eardrum.

TONGUE

The tongue is the muscular organ which lies on the floor of the mouth. It assists in tasting , mastication and swallowing of food. In an unconscious casualty the tongue tends to obstruct the throat and prevent breathing.

• Written by Manisha.
• In category Animals.
• 15 years ago.

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